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WebPart.PartCacheInvalidate method (Storage, String)

Marks the specified cache entries of the specified storage type in the Web Part cache as outdated.

Namespace:  Microsoft.SharePoint.WebPartPages
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)

protected void PartCacheInvalidate(
	Storage storage,
	string key
)

Parameters

storage
Type: Microsoft.SharePoint.WebPartPages.Storage

A Storage value that identifies the type of storage allocated in the Web Part cache to mark as outdated. Possible values are Personal and Shared.

key
Type: System.String

A value that identifies the cache entry of the specified storage type in the Web Part cache.

Calling the PartCacheInvalidate(Storage, String) method passing a Storage value and a key as arguments marks only the specified cached value of the specified storage type in the Web Part cache as outdated. Call the [M:Microsoft.SharePoint.WebPartPages.WebPart.PartCacheInvalidate()] method to mark all content of the Web Part cache as outdated. Call the PartCacheInvalidate(Storage) method to mark all content of the specified storage type in the Web Part cache as outdated.

The following code example shows a Web Part that caches and displays the time when it is first rendered, and provides a button to refresh the Web Part cache with the current time.

using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Serialization;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.WebPartPages;

namespace WebPartLibrary1
{
    /// <summary>
    /// Summary description for CacheSample.
    /// </summary>
    [DefaultProperty("Text"),
        ToolboxData("<{0}:CacheSample runat=server></{0}:CacheSample>"),
        XmlRoot(Namespace="WebPartLibrary1")]

    public class CacheSample : Microsoft.SharePoint.WebPartPages.WebPart
    {
        Button refreshButton;

        public CacheSample()
        {
            this.PreRender+=new EventHandler(UpdateCache);
        }

        protected override void CreateChildControls()
        {
            refreshButton = new Button();
            refreshButton.Text="Refresh Cache";
            refreshButton.Click+=new EventHandler(refreshButton_click);
            this.Controls.Add(refreshButton);
        }

        public void UpdateCache(object o, System.EventArgs e)
        {

            if(this.PartCacheRead(Storage.Shared,"cacheKey") == null)
            {
                this.PartCacheWrite(Storage.Shared,"cacheKey", fetchData(), TimeSpan.FromSeconds(10));
            }
        }

        private void refreshButton_click(object o, System.EventArgs e)
        {
            this.PartCacheInvalidate(Storage.Shared, "cacheKey");
        }

        protected override void RenderWebPart(HtmlTextWriter output)
        {
            output.Write("Cache Value: ");
            output.Write(PartCacheRead(Storage.Shared,"cacheKey")+ "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;");
            this.RenderChildren(output);
        }

        private string fetchData()
        {
            return DateTime.Now.ToLongTimeString();
        }
    }
}

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